Dolphin Development

From Embryology


Dolphin anatomy


Some Recent Findings

  • Seasonality, estrous cycle characterization, estrus synchronization, semen cryopreservation, and artificial insemination in the Pacific white-sided dolphin (Lagenorhynchus obliquidens). [1] "Ovulations and conceptions occurred from August to October. Peak mean serum testosterone, cross-sectional testicular area , and sperm concentration occurred in July, August, and September respectively. Spermatozoa were only found in ejaculates from July to October. Estrous cycles were 31 d long and were comprised of a 10 d follicular and 21 d luteal phase. Ovulation occurred 31.2 h after the onset of the LH surge and 19.3 h after the LH peak."
  • True hermaphroditism: first evidence of an ovotestis in a cetacean species[2] "An immature unilateral hermaphrodite common dolphin (Delphinus delphis) was found stranded on the southwest coast of the UK. The external phenotype was that of a female, but internally there was one ovotestis, containing both ovarian follicles and testicular tubular elements, and a contralateral ovary. Ovarian portions of the ovotestis appeared normal and demonstrated follicular development, whereas the testicular tissue exhibited hypoplasia and degeneration."


Suborder Odontoceti, toothed whales

  • Family Delphinidae, oceanic dolphins
  • Family Platanistidae
  • Family Iniidae
  • Family Lipotidae
  • Family Pontoporiidae


  • Common bottlenose dolphin (Tursiops truncatus)
  • Indo-Pacific bottlenose dolphin (Tursiops aduncus)
  • Burrunan dolphin (Tursiops australis)

Development Overview

Limb Development

Hind-limb loss in embryos of the dolphin.[3]

Researchers have identified that Sonic hedgehog (Shh), that in limb development is the signaling activity of the zone of polarizing activity (ZPA), is absent from the dolphin hind-limb bud. An absence of Hand2, an upstream regulator of Shh, leads to the failure to establish a ZPA.[3] The hind-limb bud initiates, but then bud arrests and degenerates around the fifth gestational week.

Dolphin limb development 02.jpg

Links: Limb Development | Sonic hedgehog


  1. <pubmed>19494046</pubmed>| Reproduction
  2. <pubmed>20708743</pubmed>
  3. 3.0 3.1 <pubmed>16717186</pubmed>| PNAS




<pubmed>20722252</pubmed> <pubmed>17957751</pubmed> <pubmed>17597550</pubmed> <pubmed>12845705</pubmed> <pubmed>4856964</pubmed>


Search PubMed

Search PubMed: Dolphin development | cetacean development

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Cite this page: Hill, M.A. (2024, June 23) Embryology Dolphin Development. Retrieved from

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© Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G